The intermediate scale measurement system (ISMS) is a state-of-the-art
measurement range for Navy structural acoustics research. The range is located
in Lake Pend Oreille at the Acoustic Research Detachment (ARD) of the Naval
Surface Warfare Center, Bayview, Idaho. The system is designed to accommodate
``high fidelity'' 1:10 to 1:4 scale models of submarines. The ISMS has several
unique measurement modes, including: (1) generation of plane-wave ensonification
using a phased planar array of 36 projectors; (2) radiated signature measurement
using a full 360-deg azimuth, 158 hydrophone, near-field receive array; and (3)
acquisition of data from up to 1000 model-mounted sensors. Through use of high
precision acoustic location measurement, the ISMS has an integral capability to
project near-field bistatic target strength and radiated noise signatures to the
far field. Based on these measurement modes, the ISMS can make very accurate,
precise and repeatable target strength, radiated noise, and structural response
measurements. The receive array is also used for the spatial imaging of the
radiated pressure fields. Selected analysis products from a 1:4 scale model test
series will be presented. [Work supported by ONR.]